Improving Cryptosporidium testing methods: a public health perspective

Cryptosporidium is a protozoan parasite found in surface waters throughout the United States. Waterborne cryptosporidiosis outbreaks may be associated with contaminated drinking water supplies. The approved method, USEPA (United States Environmental Protection Agency) Method 1623, for testing for the presence of Cryptosporidium in United States surface waters has several limitations. Firstly, recovery efficiency varies widely. Secondly, Method 1623 does not specify a mechanism for assessing the viability and infectivity of oocysts detected, or the Cryptosporidium species of the oocysts. Lastly, there are logistical limitations which are relevant to Method 1623 in particular, and to the state of the science of Cryptosporidium testing in general. Methods that give specific results more quickly, with higher recoveries and better consistency must be developed and made accessible for utilities to use. Improved Cryptosporidium testing methods can minimize uncertainty; this, in turn, will simplify the risk communication task, and the level of trust which the public has in the water utility can be maintained and improved. This paper reviews the current and ongoing research on analytical, monitoring, and sampling methods for Cryptosporidium, and identifies the needs that should be considered in future research.